U.S., Philippines Add Muscle to Military Drills

Joint exercises expand as South China Sea tensions escalate

MANILA—The U.S. military and Philippines armed forces kicked off their biggest joint exercises in 15 years on Monday, at a time of distress in Manila over China’s island-building program in the South China Sea.

The annual exercise—called Balikatan, or “Shoulder to Shoulder,” is twice the size of last year’s drill, involving more than 6,600 U.S. forces, 5,000 Philippine personnel and also 61 Australian troops, Philippine military...